Difference between revisions of "Team:Imperial College/Composite Part"

This year our best composite part is the pBAD-Gp2 construct. It provides a new way to repress growth in bacteria without killing the host cell. We have demonstrated that the cell is able to recover its initial growth rate once Gp2 is not expressed and can recover back to a normal growth rate. We are excited to provide this new growth regulator for the synthetic biology community and for the future iGEM teams.

→The protein is very small, and can inhibit growth within a half-hour timeframe.
→The repression is robust and reversible.
→The system does not require any toxins or supplements in the media.
→Usage of the gene avoids the problem of antimicrobial resistance.

Figure 1: Schematic of the pBAD-Gp2 construct

For our best composite part, we have selected the pBAD-Gp2 part. It was created by cloning a synthesised sequence block that contained Gp2, an RBS and the biobrick prefix and suffix, into an pBAD construct created by the 2014 Imperial iGEM team.

The construct effectively and rapidly downregulates the growth of E. coli in response to arabinose, and does so in a reversible manner. We believe it is a good alternative to existing growth control methods, especially for controlling co-culture, for several reasons

→Controlling cells in this way doesn’t require the usage of supplemented or minimal media, as in the case of antibiotics and auxotrophy.
→The gene is already naturally in the environment within the E.coli virus T7 phage, so there aren’t major biocontainment issues or the problems associated with antimicrobial resistance.
→It is specific to E. coli, and so, while possibly toxic to other prokaryotic bacteria, will not have any effect on eukaryotes.
→Gp2 is particularly good for regulating population size in co-cultures, as it only affects the size of one population.

Figure 2: Growth inhibition of Top10 cells by induction of Gp2 by arabinose

Figure 3: Recovery of growth by Top10 cells after induced araBAD operon is switched off by glucose-mediated catabolite repression.